The red marine alga Porphyra is high in protein, vitamins, minerals, and soluble fiber, and it is the most widely eaten and commercially valuable seaweed in the world. Commonly called “Nori,” it is commercially grown in the open seas off the coasts of Japan, China, Korea, and Taiwan on nets covering nearly 70,000 hectacres. Annual harvests result in over 130,000 metric tons, with sales totaling over $6 billion US dollars. The market for Nori sheets in the US alone is estimated to be worth at least $50 million dollars annually and is growing at a rate of over 17% per year.
The development of cultivation techniques to reduce costs, increase yield, and to enhance the levels of various nutrients in Nori has been of major importance. Some improvements made to the technical aspects of Nori cultivation include the development of techniques for controlled culturing using land-based seawater ponds and for artificial seeding of spores onto cultivation nets, which can be stored until placed in the ocean.
With approximately 70 species of Porphyra worldwide, genetic improvement of cultured species has also been crucial for maximizing yield and developing cost-effective cultivation programs. To this end, classical breeding methods, particularly strain selection, have been the most successful at improving seaweed cultivation techniques. For example, as a result of strain selection efforts, there are several dozen cultivars of two Porphyra species, P. yezoensis and P. tenera, farmed in Japan. These cultivars were developed primarily as a result of an intensive strain selection program in Japan. Over many years of repeated selection, improvements were made in increasing the average length of fronds, as well as the length of the growing seasons of these two species.
Despite the success of such efforts to improve cultivation techniques, there are still a number of challenges, disadvantages, and limitations. In particular, repeated strain selection usually requires many years of intensive effort and is very labor intensive. Thus, selecting particular strains of Porphyra that yield desired levels of various nutrients can be difficult. In addition, the existing genetic variability in one or more populations of interest may not be sufficient for strain selection purposes. This can limit strain selection techniques to those varieties with high genetic variability, potentially foreclosing the use of strains that may contain desirable nutrient levels but that may not have the genetic variability suitable for strain selection.
What are needed are methods that allow one to obtain multiple types of Porphyra compositions without the need to cultivate multiple strains of Porphyra. Also needed are methods that can be used to produce specific and tailored Porphyra compositions but that minimize the use of specialized cultivation or strain selection techniques. Compositions prepared from such methods, and methods of using such compositions are also needed. Disclosed herein are compositions and methods that meet these and other needs.